Lab-scale investigations on the processing of small powder volumes are of special importance for applications in additive manufacturing (AM) techniques. Due to the technological importance of high-silicon electrical steel, and the increasing need for optimal near-net-shape AM processing, the aim of this study was to investigate the thermal behavior of a high-alloy Fe-Si powder for AM. An Fe-6.5wt%Si spherical powder was characterized using chemical, metallographic, and thermal analyses. Before thermal processing, the surface oxidation of the as-received powder particles was observed by metallography and confirmed by microanalysis (FE-SEM/EDS). The melting, as well as the solidification behavior of the powder, was evaluated using differential scanning calorimetry (DSC). Due to the remelting of the powder, a significant loss of silicon occurred. The morphology and microstructure analyses of the solidified Fe-6.5wt%Si revealed the formation of needle-shaped eutectics in a ferrite matrix. The presence of a high-temperature phase of silica was confirmed by the Scheil–Gulliver solidification model for the ternary model Fe-6.5wt%Si-1.0wt%O alloy. In contrast, for the binary model Fe-6.5wt%Si alloy, thermodynamic calculations predict the solidification exclusively with the precipitation of b.c.c. ferrite. The presence of high-temperature eutectics of silica in the microstructure is a significant weakness for the efficiency of the magnetization processes of soft magnetic materials from the Fe-Si alloy system. For the electromagnetic properties of Fe-Si soft magnetic alloys to be optimal, silicon content of 6.5 wt.% is the most effective. This level of silicon concentration ensures near-zero magnetostriction, low electric losses, high permeability, and high electrical resistivity ,2,3,4. HA challenge that needs to be overcome is how to process magnetic materials and components that contain 6.5 wt% Si 11 at% Si) beyond the current technological routes 1 at% Si ,8,9,10. Over the past few years, metal AM has been growing remarkably. AM, a layer-by-layer three-dimensional (3D) printing technology, has opened up new possibilities for improvements in the industrial manufacturing of electrical machines via the near-net-shape printing of complex geometries, tailored structure–composition–property relationships, a reduction in the part count and the production lead time, and the conservation of expensive critical raw materials ,17,18,19The AM of ferromagnetic alloys has received much attention because of its potential to produce functional parts ,20,21. PMetal AM can use different forms of feedstock, with powders and wires being the most common. The selection of feedstock type has a great impact on (i) the overall cost of the process, (ii) the print speed and resolution, and (iii) the quality and safety .3C in the area of ordered phases [An important shortcoming of AM techniques is the cracks that appear very frequently . The hetd phases . Howeverd phases .Despite its potential benefits, AM still presents several challenges, including expensive processing costs, post-processing difficulties, and supply chain maturity issues ,22,23,24Numerous studies have been conducted on alloys, but unfortunately, many of them lack crucial details on the mechanical and magnetic properties of these materials. These properties are of significant importance when it comes to understanding how alloys perform under different conditions. Thus, it is essential to conduct further research and tests on various alloy systems, particularly the emerging advanced alloys and composites found in the complex concentrated alloy or high-entropy alloy space. It is also crucial to test integrated electromagnetic machine components that utilize magnetic cores enabled by unconventional processing techniques. By doing so, researchers can gain a better understanding of how these alloys and components can be optimized for maximum performance .At present, the metallurgical market offers electrical steel, a product that is commonly a sheet or strip with a silicon content of less than 4 wt%. However, with the advances in modern electrical machinery, there is a growing demand for high-silicon Fe-Si alloys that exhibit exceptional magnetic properties. As a result, the present study focuses on improving the processability of high-alloy Fe-Si powder and, consequently, the magnetic characteristics of such alloys.Due to the technical importance of Fe-Si alloys, the study involved analysing the thermal behaviour of an Fe-6.5wt% Si alloy powder through simultaneous thermal analysis. By doing so, the researchers were able to gain a better understanding of the thermal properties of the alloy and identify areas where improvements could be made. Ultimately, the aim of this research is to support the development of high-performance Fe-Si alloys that meet the specific requirements of modern electrical machinery.For representative powder particles sampling, the simple random sample method was chosen. Two hypotheses were set: (i) each unit in the population has an equal possibility of being selected and (ii) the sample properties are a true reflection of the population’s properties .Samples of Fe-6.5wt%Si alloy powder were further investigated by means of chemical analyses, metallography, and thermal analysis. For chemical analyses, a sample mass of 1 g was taken. For the FE-SEM/EDS metallographic examination, samples were taken randomly using carbon tape. For thermal analysis, a sample mass of 1 g was taken.Sampling from a population with an arbitrary distribution of the attribute was conducted to determine the silicon content in the selected samples of the DSC-remelted bulk of an Fe-6.5wt%Si alloy. Here, the elements of a population are characterized by a measurable attribute  . For cheThe chemical compositions of the randomly selected samples (of 1 g in weight) were determined using an optical emission spectrometer with inductively coupled plasma , an Agilent 5800 VDV instrument , and combustion methods using an ELTRA CS-800 analyser for carbon and sulphur estimation . Furthermore, Si content in the as-received powdered alloy samples and the remelted Fe-6.5wt%Si bulk samples was additionally determined by gravimetric and classical analytical methods.Metallographic analyses FE-SEM/EDS were performed using a scanning electron microscope JEOL JSM-6500F . FE-SEM/EDS analyses of the powder particles were performed at an accelerating voltage of 15 kV.Optical imaging was performed using a ZEISS Axio Imager Z2M  optical microscope.Samples under investigation were randomly selected powder particles and metallographic cross-sections of the DSC-remelted bulk samples of Fe-6.5wt%Si.Thermodynamic calculations were performed using the Thermo-Calc  software package 2017a and the database TCFE8:Steels/Fe-Alloys v8.1. A computer simulation of the solidification of the selected binary Fe-6.5wt%Si alloy was performed with the Scheil–Gulliver model . For comThe thermal behavior of the soft magnetic alloy powder for AM was investigated using differential scanning calorimetry (DSC) with a STA-449 C Jupiter instrument, Netzsch .The dynamic measurements involved two consecutive cycles at the same selected ramp rate, i.e., 10 K/min. The linear temperature program for heating and cooling was as follows: 25 °C–1550 °C–350 °C–1550 °C–25 °C. A regular temperature calibration was conducted using technically pure metals at 10 K/min as a medium scanning rate using an argon atmosphere . For a low-temperature region, In, Sn, and Al were used. In the case of the high-temperature region, the calibration involved Au and Ni. Measurements of temperature were made using S-type thermocouples (for the furnace as well as the sample carrier control). Accordingly, the DSC experiments were conducted under a static argon atmosphere. There was no isothermal annealing performed at the maximum temperature. Two cycles were used to achieve better thermal contact between the two forms of specimens  and the crucible.DSC experiments were conducted in three parallels; randomly selected samples (1 g in weight) were designated as #1, #2, #3.The chemical compositions of the selected samples of Fe-6.5wt%Si alloy powder are shown in Further characterization of the Fe-6.5wt%Si powder using SEM/EDS revealed oxidized surfaces of the randomly selected metal particles . InformaThe measurements show that the concentrations of powder particles, specifically the Si content, vary in relative amounts. However, it is essential to focus on the final concentration of the prepared material rather than the precursors used. The uneven distribution of the element in the sphere and the teardrop-shaped interaction volume of the EDS can cause variations in the measured values. At the 15 kV accelerating voltage, the EDS can penetrate the surface from less than 100 nm up to a depth of 2 μm. The theoretical detection limits in SEM–EDS measurements are about 0.1 wt.%.Due to the SEM-EDS results showing oxidized surfaces of the Fe-6.5wt%Si alloy powder, TD equilibrium and Scheil–Gulliver solidification modelling were performed for two alloys: the binary model Fe-6.5wt%Si alloy and the ternary model Fe-6.5wt%Si-1.0wt%O alloy.The simulations are graphically shown in In the DSC experiments, the samples of the soft magnetic Fe-6.5wt%Si alloy powder were linearly heated at 10 K/min above the liquidus temperature to allow their melting behavior to be monitored. Cooling at the same ramp rate allowed the solidification sequence to be monitored. Linear heating and cooling at the selected ramp rate were repeated in two consecutive cycles.In It is assumed that the first endothermic peak at approximately 698 °C in the DSC melting curves see  represenEven more interesting was the DSC cooling curve for sample #1, represented in It is clear that sample #1 contained a fraction of unknown high-temperature phase(s). When an alloy contains only a small fraction of the high-temperature phase, determining the liquidus temperature in DTA and DSC measurements can be very challenging . HoweverSince the second cycle of the DSC experiments did not show the presence of high-temperature phase(s), we can conclude that the surface-oxidized alloy powder was sufficiently degassed (deoxidized) during the processing stage in an Ar atmosphere (processing via melting–cooling–remelting–cooling).In Due to the rather slow cooling rate and very low impurity content, especially of carbon, the typical remelted and solidified microstructure consists of large polygonal ferrite grains, where the diameter of individual grains reaches up to several millimeters. Shrinkage porosity visible in the form of large, black, round spots and many small precipitates are present. However, a detailed look at the solidification microstructure reveals the obvious substructures in the underlying ferrite matrix . FurtherIn addition, after the DSC processing of the soft magnetic Fe-6.5wt%Si powder alloy, chemical analysis revealed a noticeable silicon loss (>5%). The results are listed in A significant evaporation of Si during annealing was also reported in the study of Tian et al., where Fe-6.5wt%Si sheets were prepared based on various processes, including magnetron sputtering .The metallographic characterization of the Fe-6.5wt%Si powder revealed the surface oxidation of spherical particles . Both thThe solidification microstructures of the model Fe-6.5wt%Si alloy, the oxidized Fe-6.5wt%Si alloy powder, and the conventional high-silicon electrical steels are certainly comparable.The solidification microstructure of all of the selected alloys consists of a b.c.c.-ferrite matrix. However, the microstructure of the model Fe-6.5wt%Si alloy is fully ferritic , whereasThe presence of high-temperature oxides or eutectics is definitely not the case in conventional high-silicon electrical steels , as obseThe experiments showed that the chemical compositions of the analyzed samples of the Fe-6.5wt%Si alloy powder differ from each other.According to relevant TD calculations, the model binary Fe-6.5wt%Si alloy solidifies with the primary form of b.c.c. ferrite.However, during the solidification of some Fe-6.5wt%Si alloy powder under investigation, the DSC measurements revealed the precipitation of not only b.c.c. ferrite, but also of a small fraction of high-temperature phase(s).Due to the high affinity of Si for oxygen, and the large surface area of the alloy powder, it can be concluded that the high-temperature phases are silica polymorphs.Metallographic analyses on the remelted and solidified Fe-6.5wt%Si alloy powder revealed the formation of needle-shaped eutectics in the ferritic matrix.In addition, a significant loss of silicon through remelting was measured.


Objectives: High-intensity interval training improves aerobic endurance, but the effectiveness of different training protocols is unclear. This study compared the effects of running-based high-intensity interval training (R-HIIT) and body weight-based high-intensity interval training (B-HIIT) on physical fitness in adolescents.Methods: This was a pre-and post-test quasi-experimental design in which a seventh-grade natural class was randomly selected from three homogeneous middle schools, and then the three natural classes were randomly divided into three groups: the R-HIIT group (n = 54), the B-HIIT group (n = 55), and the control group . Both intervention groups exercised twice a week for 12 weeks with a 2:1 (1 min:30 s) load-interval ratio and exercise intensity controlled at 70%–85% maximum heart rate. R-HIIT was in the form of running, and B-HIIT was in the form of resistance exercises using the participants’ body weight. The control group was instructed to continue their normal behavior. cardiorespiratory fitness, muscle strength and endurance, and speed were measured before and after the intervention. Statistical differences between and within groups were determined using repeated measures analysis of variance.Results: Compared to the baseline, both the R-HIIT and B-HIIT intervention groups significantly improved CRF, muscle strength, and speed (p < 0.05). The B-HIIT group was significantly better than R-HIIT in improving CRF , and only the B-HIIT improved sit-up muscle endurance .Conclusion: The B-HIIT protocol was significantly more effective than the R-HIIT protocol in developing CRF and improving muscle health indicators. Participation in regular physical activities (PA) promotes the physical , psycholSchool physical education (PE) lessons provide opportunities for children and adolescents to participate in physical activity and promote their health, but, due to curriculum and personal reasons, each student only participates in exercise between 18% and 50% of the total time in a PE lesson . TherefoResearchers and the public have paid much attention to high-intensity interval training (HIIT) in recent years because it can produce physiological benefits similar to MICT in a shorter time . HIIT prAccording to Despite these prospects, many of these studies pay attention to the effect of HIIT on cardiorespiratory fitness (CRF) and cardiovascular metabolism but do not assess the impact on musculoskeletal health. The current international consensus is that it is important to include musculoskeletal health in the adolescent health assessment . Second,Body weight-based high-intensity interval training (B-HIIT) has received a lot of attention in recent years because it does not require specialized equipment and can be performed with minimal space. Evidence has shown that, under proper supervision, resistance exercises based on one’s own weight, do not negatively impact the growth and development of children and adolescents and can also improve related health indicators and reduce the risk of injury . Some stFurthermore, many current health promotion initiatives for children and adolescents emphasize increasing PA levels, and knowledge of the factors influencing PA levels is limited to psychological, social, and environmental aspects , omittinGiven that adolescent health is directly tied to both increasing daily PA levels and improving adolescent physical fitness levels, this study had two objectives. The primary objective of this was to investigate the effects of two HIIT protocols (R-HIIT and B-HIIT) on adolescent physical fitness in order to establish an intervention framework that would more effectively promote healthy adolescent development. We hypothesize 1 that B-HIIT is better than R-HIIT in improving the physical fitness index of adolescents because it emphasizes using and controlling one’s weight, which can activate more muscles than R-HIIT and impose significant physiological stimulation on the body . The secThis was a pre-and post-test study using a quasi-experimental design with the addition of a control group. The 12-week intervention was conducted from September to December 2018. Based on our school-based recruitment through consultations with nearby pediatricians, convenience sampling was used. The following factors guided our decision to choose three middle schools in Beijing, China, as intervention centers: The schools were all coeducational, had comparable teacher-student ratios, teacher qualification standards, and teacher experience levels, were all public schools that followed the same educational curriculum, and each student in each school had similar household income and parental education levels. In addition, all the schools had adequate space for both indoor and outdoor physical activity.The inclusion criteria for subjects in this study were 1) age 11–13, as this age group was underrepresented in previous studies, 2) no regular physical activity other than physical education classes within 3 months before the experiment, and 3) no contraindication to any exercise. Criteria for exclusion were: 1) exercise contraindications or restrictions; 2) acute illness or sports injuries; 3) psychiatric or other psychological disorders, and 4) congenital or acquired heart disease. All subjects were informed of the risks and requirements of the training program, and we obtained signed informed consent from the students and their guardians before the start of the study. The trial was approved by the Ethics Committee of the Capital Institute of Sports  and registered in the Chinese Clinical Trial Registry (registration number: ChiCTR-IOR-17010435).n = 54), B-HIIT group (n = 55), and control group . To mitigate potential confounding effects between the intervention and control groups, randomization was not conducted at the individual level within the schools , which has been shown to have strong validity in Asian children  and has 2max (2max was then estimated using the following formula:speed is that corresponding to that stage (speed = 8 + 0.5 stage no.), age is in years.The multistage 20-m shuttle run test was used to estimate VO2max . SubjectTo test for secondary outcomes, we used the standing long jump, vertical jump, handgrip strength test, 30-s sit-up test, and 50-m sprint. The standing long jump has been shown to be a valid assessment of explosive power . ParticiThe vertical jump is a valid measure of muscle strength and is positively correlated with bone structural strength and mineral content . SubjectTo assess the health and function of adolescents’ musculoskeletal systems, handgrip strength is a trustworthy indicator . A BaselThe sit-up 30-s test assesses the muscular endurance of the trunk . The subThe 50-m sprint is used to assess the speed and anaerobic capacity . On the An extensive process evaluation was conducted to assess the feasibility and fidelity of the intervention. The intervention center faculty completed daily monitoring reports of the activities to ensure the quality of the interventions. Also, subjects were randomly selected from the intervention and control groups to wear an ActiGraph wGT3X-BT accelerometer  for 1 week during the intervention, for the purpose of assessing differences in physical activity levels, and patterns between groups.The accelerometer was attached to a wrist strap and subjects were required to wear the accelerometer on the wrist of the non-dominant hand for 7 consecutive days, including 2 weekend days for at least 10 h a day except when swimming or bathing . The subThroughout the 12-week study period, the intervention group participated in two 45-min regular PE classes per week, conducted by the school’s PE teacher and following the regular curriculum. The R-HIIT and B-HIIT groups received the intervention from two trained and qualified physical education teachers, and two topic experts oversaw the procedure to ensure that the intervention was carried out correctly. The intervention group replaced the warm-up exercises in the regular program with the proposed HIIT training session and then continued to complete the planned normal PE session.HIIT sessions were performed during the first 10–15 min of each class, including a short warm-up, with a total of 8–10 interventions, using a 2:1 (1 min:30 s) work-to-rest ratio, with exercise intensity controlled at 75%–85% of maximum heart rate. A Mio Alpha heart rate monitor , was used to monitor heart rate changes per second during exercise. We utilize the computer to track changes in the subjects’ heart rates as reported in real time by the heart rate monitor. When a subject’s heart rate falls short of the target heart rate, the research team members would remind them to intensify their exercise intensity in order to reach the desired heart rate. A work-rest ratio of 2:1 is optimal for male and female participants in HIIT , and exeThe specific intervention for the R-HIIT group was a “real-world” training program based on a 20-m shuttle run test called “beep training” . A flat The PE teacher led the B-HIIT group in performing the full-body resistance exercises along with the rhythm of the music. Movement patterns included jumping jacks, jumping lunges, burpees, air squats, mountain climbers, and high knees. After 4 weeks of the experiment, as the subjects’ training heart rate improved relative to the target heart rate, movement frequency was increased according to the improvement in the students’ exercise ability Throughout the 12-week intervention period, the control group participated in regular 45-min PE classes twice a week, following a normal curriculum with the PE teacher.The present study had high fidelity. Monitoring reports and researcher observations of the intervention groups showed that, with very few exceptions, the participants adhered to the weekly unit plan and a daily instructional plan developed in the study and controlled the intensity of the intervention through heart rate monitoring. The total exercise time and HIIT intervention time remained consistent for each group. Attendance averaged over 90% for each session.2max). The sample size required for each group was calculated to be 20. Considering a 20% dropout rate, we established the minimum number of subjects in each group as 22.We used other relevant studies to estimate the number of subjects needed for the experiment. Based on previous research , we set p2, in which a small effect was 0.20, a medium effect was 0.50, and a large effect was 0.80. The significance level was set to p < 0.05.This study adopts the principle of intention-to-treat analysis. The collected data were analyzed using IBM SPSS Statistics 26 software. All data were represented as mean ± SD, and the normal distribution test and variance homogeneity test were carried out by the Shapiro-Wilk test and Levene test, respectively. One-way analysis of variance  and Chi-square test (gender) was used to test the differences in demographic variables. Sex, age, and BMI are controlled as covariates. The 3  × 2 (time: pre- and post-test) repeated measurement analysis of variance was used to test the difference before and after intervention for the experimental groups. When the interaction of group × time or the main effect of time and group was significant, a simple effect analysis was used to make a statistically significant pairwise comparison (Bonferroni). In addition, the effect size with statistical significance was calculated, which was expressed as ηn = 21) or were unwilling to participate (n = 14). Of the test subjects, 71 were male and 92 were female. No injuries were reported during the 12-week intervention period, but one male and one female dropped out of the R-HIIT group and one male dropped out of the B-HIIT group, for a total of three dropouts (1.81% rate). No significant differences were found in the baseline demographic characteristics of the two groups, as shown in As shown in 2max = 42.91, p < 0.001, ηp2= 0.35). A simple effects analysis showed significantly greater improvements in the mean performance of VO2max in both the B-HIIT and R-HIIT groups after intervention (p < 0.01), as compared to the control, with the highest scores in the B-HIIT group. Regarding the mean within-group changes, both the B-HIIT and R-HIIT significantly increased the mean VO2max from pre-to post-tests (p < 0.01), and the control group did not (p > 0.05)  .= 6.75, p = 0.01, ηp2 = 0.04), vertical jump  = 38.120, p < 0.001, ηp2 = 0.33), handgrip strength  = 11.51, p < 0.001, ηp2 = 0.21), sit-up  = 16.81, p < 0.001, ηp2 = 0.18) and 50-m sprint ) = 11.063, p < 0.001, ηp2 = 0.11) had significant interaction effects. The simple effects analysis showed significantly greater improvements after intervention in the mean performance of standing broad jump (p < 0.01) in both the B-HIIT and R-HIIT groups, and vertical jump (p < 0.01) and sit-up (p < 0.05) performance in the B-HIIT, as compared to the controls. In addition, the mean scores for vertical jump (p < 0.01) and sit-up (p < 0.05) were significantly greater in the B-HIIT group than in the R-HIIT after the intervention. Regarding the mean within-group changes from pre-to post-tests, with the exception of sit-ups which had significant improvement (p < 0.01) only in the B-HIIT group, both the B-HIIT and R-HIIT significantly increased the mean scores for standing broad jump (p < 0.01), vertical jump (p < 0.05), handgrip strength (p < 0.05), and 50-m sprint (p < 0.05), but not the control group (p > 0.05)  .p < 0.05). As shown in (p < 0.05). There was no significant difference in physical activity levels between the three groups at the weekend (p > 0.05).Measurement of weekly physical activity levels during the intervention showed that adolescents participating in the B-HIIT and R-HIIT groups had significantly lower levels of sedentary behavior and low activity  on schooshown in , the intIn this study, both HIIT protocols based on the school environment were successful in improving indicators of adolescent cardiorespiratory fitness and muscular strength, and the intervention group engaged in more moderate to vigorous exercise than the control group did throughout the intervention period. However, it was also discovered that the B-HIIT group, which relies on body weight alone, is more efficient than the R-HIIT group, which relies on running, at enhancing CRF, explosive leg strength , and abdominal muscular endurance (Sit-up). Hypothesis 1 of our study has been confirmed, but hypothesis 2 of our study is not true.Research has shown the ability of R-HIIT in the school setting to improve aerobic endurance . Our stuPrevious studies of children and adolescents in and out of school have found that when R-HIIT is used, the improvement in aerobic endurance is similar to or slightly lower than that of MICT, depending on the participants’ initial health level and the duration and design of the intervention . However2max after HIIT intervention  program. This study suggests that just 10 min of HIIT training twice a week in the limited setting of school PE classes can effectively improve the CRF and muscle strength of adolescents.


Millimeter wave fixed wireless systems in future backhaul and access network applications can be affected by weather conditions. The losses caused by rain attenuation and antenna misalignment due to wind-induced vibrations have greater impacts on the link budget reduction at E-band frequencies and higher. The current International Telecommunications Union Radiocommunication Sector (ITU-R) recommendation has been widely used to estimate rain attenuation, and the recent Asia Pacific Telecommunity (APT) report provides the model to estimate the wind-induced attenuation. This article provides the first experimental study of the combined rain and wind effects in a tropical location using both models at a frequency in the E band (74.625 GHz) and a short distance of 150 m. In addition to using wind speeds for attenuation estimation, the setup also provides direct antenna inclination angle measurements using the accelerometer data. This solves the limitation of relying on the wind speed since the wind-induced loss is dependent on the inclination direction. The results show that the current ITU-R model can be used to estimate the attenuation of a short fixed wireless link under heavy rain, and the addition of wind attenuation via the APT model can estimate the worst-case link budget during high wind speeds. Fixed wireless links using millimeter waves (mm-waves) and terahertz (THz) have been considered for use in both fifth-generation 5G) and sixth-generation 6G) wireless systems, for example, in the applications of point-to-point links in the backhaul and access networks ,2,3,4,5.G and sixG wirelesWireless channel modeling may be achieved via machine learning techniques ,12. In aIn this paper, we studied the concurrent rain and wind effects, which is the first study of this kind for E-band FWS links in a tropical location. To date, the only wind-induced attenuation model, caused by antenna vibration, relied on the experimental data in Japan , which hThe map of the experimental area is shown in The equipment and their connections are also shown in f = 74.625 GHz of the link from site 2 to site 1 was selected in the experiment. Automatic gain control (AGC) was turned off so that real-time attenuation due to weather effects could be measured. The antennas are COMMSCOPE-VHLP1-80 with a diameter of 0.3 m, beamwidth of 0.9°, 43.5 dBi gain, 14.0 dB return loss and a Voltage Standing Wave Ratio (VSWR) of 1.50. The total weight of each antenna and its mounting bracket is 7 kg. The pair of accelerometers (IMV-VP-8013M) measured 3-axis accelerations with a sensitivity of 44.9 mV/(m/s2). Their responses are in a range of 0.04–1000 Hz. The maximum measurable acceleration is ±58.8 m/s2. The RSSI level from the FWS unit and accelerometer data were sampled via the data logger (GRAPHTEC-GL980 midi LOGGER) at 10 ms intervals. Each data logger input has a 16-bit ADC with 0–30 V input range and 0–200 kHz frequency response.The followings are the specifications of the equipment. The FWS unit is NEC iPASOLINK EX Advanced, with a minimum Tx power of −5 dBm and frequencies of 71–76 GHz and 81–86 GHz. The carrier frequency 2 and can measure the rain rate in a range of 0–200 mm/h. Each value of the rain rate is a running 1-min average in 10-s intervals. The wind sensor can measure the wind speed in the range 0–60 m/s at a resolution of 0.1 m/s, with a response time of 0.25 s. Wind direction information can also be gathered with ±3° accuracy at 10 m/s. The weather sensor data were sampled at 10-s intervals using a Raspberry Pi.The weather sensor (VAISALA-WXT536), located at site 1, can measure barometric pressure, air temperature, relative humidity, precipitation, and wind. The precipitation sensor has a collection area of 60 cmBased on the E-band FWS experiment setup in this work, the signal-to-noise ratio should be affected by antenna gains, free-space loss, gaseous loss, rain attenuation and attenuation via wind effect, given usingThe first three parameters, the transmit power  are thermal noise, the total system noise figure and the margin, respectively. These parameters can be estimated for a given link as follows. The thermal noise is calculated asThe values of losses in the link budget equation, excluding rain and wind-induced attenuation, are summarized in The rain attenuation can be calculated from the rain rate using the empirical model in the ITU-R P.838-3 recommendation ,14. The The distance factor endation , given aendation . The forendation ,32. For The specific attenuation in Equation (10) is determined using the rain rate. However, previous studies have shown that smaller rain drop sizes, associated with lower rain rates, cause higher attenuations in the E band . Thus, wWindy conditions cause dynamic load on the pole and antenna structure, leading to dynamic inclination and antenna misalignment. It has been shown in the APT-AWG-REP-81 report  that theerred to . Figure Precise measurement of the inclination angle allows for an accurate estimation of the link performance in the parameter G-REP-81  and Z.K.G-REP-81  used thePole inclination, The dynamic inclination is caused by the natural vibration frequency of the pole and is given using3), 4).The wind load coefficients for static and dynamic inclination, 3, is calculated from the average temperature and pressure using the ideal gas law. The Young’s modulus, 9 Pa, is typical of stainless steel SS400. The second moment of area can be calculated to be 1.8 × 10−4 m4 for the annulus cross-section of the pole [For this setup in y, using  and takithe pole .The dynamic pole inclination angle can be directly measured using the setup in The results in endation  of R0.01The cumulative distribution function of the wind speed during the same period was plotted in One of the major sources of the attenuation in the FWS link budget calculation is the attenuation due to rain, as discussed in In addition, we have compared the measured data with the ITU-R model for rain attenuation by using the following models: ITU-R P.838 , ITU-R Pθ) versus wind direction are shown in Firstly, the effect of wind direction is demonstrated. The plots of the inclination angle , as seen in 0.01 = 83.20 mm/h) in The attenuations at longer path distances can also be estimated under various weather conditions, as shown in Sudden changes in RSSI, such as a rising or dropping of up to 1–2 dB, have been observed occasionally after gusty periods. We have attributed this effect to misalignment and realignment caused by wind gusts. The definition of such misalignment is the decrease or increase in RSSI beyond the threshold (As seen in This article presents the first field trial of the E-band FWS link in a tropical location which considers the combined rain attenuation and wind-induced attenuation. The data were analyzed using the current ITU-R P.530-18 rain attenuation model and APT-AWG-REP-81 wind-induced attenuation model. The data showed wind-induced attenuation is significant in this frequency region. By combining both models, the worst-case link budget could be estimated. Although the pole inclination angle and thus the wind-induced attenuation can be estimated via wind speed using the APT report, the direct inclination angle measurements enabling detailed weather effects which account for different inclination directions can be applied to new locations with different weather conditions. Further work can be performed to study the practical effects of wind and rain in FWS link performance, and to develop a compensation technique to ensure stable performance.


The sensitivity of MSC-based detectors and pulse shape generated by X-rays are enhanced at various bias voltages. The synthesized MSC detectors generate direction-dependent photocurrents, which indicate the presence of a polarization-induced internal electric field. In addition, photocurrent signals are produced by X-rays with energies greater than 1 MeV under a zero-bias voltage. This work demonstrates a high application potential of perovskites as self-powered detectors for X-rays with energies exceeding 1 MeV.Perovskite single crystals are actively studied as X-ray detection materials with enhanced sensitivity. Moreover, the feasibility of using perovskites for self-powered devices such as photodetectors, UV detectors, and X-ray detectors can significantly expand their application range. In this work, the charge carrier transport and photocurrent properties of MAPbBr The detection of X/γ-rays is widely used in various applications, such as medical diagnostics, material characterization, radiotherapy, astronomy, and nuclear power plants ,2,3,4. A3 single crystal (MSC) surface passivated by a UV–O3 method with a sensitivity of 80 μC Gyair−1 cm−2 in 2016. In 2019, Li [air−1 cm−2 by performing an additional MSC annealing process. Several studies were conducted to increase the detection sensitivity even further [2(MA)2Pb3Br10 and P(VDF–TrFE)/perovskite bulk heterojunctions, respectively. Wang [4Pb3Cl10 2D hybrid perovskite, and self-powered X-ray detectors were investigated by other research groups [Sensitivity is an important figure of merit of X-ray detectors because high sensitivity allows the detection of low-dose X-rays, which decreases the patient dose . For thi2019, Li  achieved further ,18,19; h further . The dif further  and thei further ,22. Liu  further  and Cao  further  examinedly. Wang  detectedh groups ,27. The h groups ,29. The h groups ,30,31. Hh groups ,33,34.In this study, we enhanced the MSC sensitivity by processing the MSC surface and then confirmed the feasibility of employing self-powered MSCs for the detection of X-rays with high energies exceeding 1 MeV, which are commonly used in medical radiotherapy. For this purpose, we treated the as-grown MSCs with different mechanochemical processes to increase the detector sensitivity and then compared the electrical, structural, photo-responsive, carrier transport, and defect properties of the resulting materials. Additionally, an ohmic contact was formed using an Au electrode to improve the MSC sensitivity, and the responses of the fabricated MSC detectors were determined by conducting X-ray irradiation studies.2  were weighed at the same molar ratio and dissolved in N,N-dimethylformamide  to prepare an MSC precursor. The obtained mixture was stirred at 300 rpm at room temperature for 24 h to completely dissolve the precursor components. After that, it was filtered with a 0.2-μm poly(tetrafluoroethylene) filter followed by heating at a rate of 2 °C per day. The produced MSC was extracted when the crystal reached a desired size, and the remaining solution was repeatedly used for the subsequent growth processes. A seed was placed at the beaker bottom to grow a new MSC in the previously used solution because no differences were observed between the XRD patterns of the seedless and seed-grown MSCs.The perovskite MSCs were grown using a modified ITC method . First, 2O3 + ethanol, Al2O3 + ethylene glycol, or glycerin. The processed MSCs were classified into the lapped-only, Al2O3 + ethanol-polished, Al2O3 + ethylene glycol-polished, and glycerin-polished MSCs, followed by rinsing with hexane. The Ag and Au electrodes were deposited by applying Ag paste  and Au evaporation, respectively. The contact between the MSC and PCB board was established using the Ag paste and Au line  with a thickness of 50 μm.Different mechanical treatments were performed on the as-grown MSCs. To eliminate a protruding part and flatten the rough MSC surface, all MSC specimens were mechanically lapped with 1200-grit SiC sandpaper followed by chemo-mechanical polishing with AlThe crystal structures of the fabricated MSC and its powder were determined by XRD using an Ultima/SmartLab diffractometer . The MSC energy band diagram was obtained by UPS and UV-visible spectroscopy using Thetaprobe  and Cary 5000  instruments, respectively. The steady-state PL spectra were recorded by a MicroTime-200  confocal microscope. The current–voltage characteristics were determined with a Keithley 237 source meter for the measurements of dark current and photocurrent using a radioisotope or fluorescence lamp. The hole mobility–lifetime products were calculated by fitting the photocurrent values measured using the Am-241 isotope with an initial radioactivity of 91.62 μCi with the modified Hecht’s equation.3 [2.All X-ray simulations were conducted using the Matlab R2020b software. The calculated current depending on the detector resistivity  was set 3 . During 3” are clearly visible on its surface despite the high MSC thickness of 2.3 mm. The crystallinity and band structure of the produced MSC were determined by X-ray diffraction (XRD), ultraviolet photoemission spectroscopy (UPS), and UV-visible spectroscopy. 3.The inset of cut-offE) was measured by UPS (gE). The Fermi level (fE) was calculated by subtracting cut-offE (16.3 eV) from the energy of incoming photons (21.22 eV). Valence band maximum (VBME) and conduction band minimum (CBME) were calculated considering both cut-off lines in VBME, CBME, and fE values are equal to −5.73, −3.51, and −4.92 eV, respectively. To examine the bandgap characteristics of the MSC, its secondary electron cut-off energy  of each surface were determined to be 58.36 nm, 106.03 nm, and 36.29 nm, respectively, which demonstrates a significant difference in the surface roughness depending on the type of polishing abrasives. In particular, the samples polished by either Al2O3 + ethanol or Al2O3 + ethylene glycol had an irregular surface with distinct valleys and hills  depending on the lateral distance (x axis) of samples. In addition, samples with low surface roughness minimize diffuse reflection, allowing visible photons to pass through the sample, making the sample more transparent  studies, as shown in inset of a. Additiρ) values (I) generated by radiation was set to exactly 2, as explained in I2) is lower than that of the high resistivity detector (∆I1) because the dark current (or leakage current) disturbs the measurements of the onI and offI terms in onI and offI. Thus, the high leakage current results in different photocurrent values measured under the same illumination conditions, deteriorating the precision and performance of the detector.) values . At eachV) is applied to the electrode for the collection of photogenerated carriers, different electric fields are generated in the regions with different crystal thicknesses. For example, in e1 and e2 are the photogenerated electrons that are fully identical except for their locations. These electrons are collected by the electric force produced by the electric field. However, they travel different distances (d1 ≠ d2), indicating that the electric fields in these two areas are also different (E1 ≠ E2) at the same bias voltage (V = V1 = V2) (qE(enμ + hpμ)  d. Furthee + pμh) . Thus, t2O3 + ethanol or Al2O3 + ethylene glycol mixture because the diffuse reflection from the MSC surface reduced the PL intensity. Only the glycerin-polished MSC demonstrated good hole transport properties (h) is considered an invariant value that does not depend on the surface treatment process because it represents a bulk property [h values of the other MSCs depicted in According to Ref. , the suroperties c, which property . Howeverproperty ,41. The I) should become saturated at a certain bias voltage, while the photocurrent increase rate gradually decreases with increasing bias because the intensity of visible light produced by the fluorescence lamp is limited and constant. However, only the glycerin-polished MSC exhibits the above-mentioned tendency , as shown in I). Therefore, we designed the Au/MSC/Au structure with an ohmic contact .To improve the device sensitivity, the Ag electrodes were replaced with Au electrodes a. The Ag contact b between contact c. Thus,  contact d is clos contact d–f, despf 0.9969 e. FigureAdditionally, we measured the signal generated by X-rays with an energy of 70 keV at a zero bias . AmazingTo examine the attenuation properties of MSCs in the high-energy range, additional simulations were conducted a–c. The The radiation produced by high-energy X-rays is different from that of soft X-rays. Because the secondary electrons generated by the primary incoming X-rays have a relatively high energy, they penetrate materials on the centimeter scale, although the secondary electron is the volumed particle ,48. ThusIn this study, we investigated the effect of mechanochemical surface treatment on the MSC detection performance and significantly increased the MSC sensitivity using the Au/MSC/Au configuration. The glycerin-polished MSC exhibited the highest PL intensity and transmittance rate of visible light as compared with those of the other treated MSC samples, which indicated high mobility-tau product, surface roughness, and higher photocurrent from visible light. The sensitivity of the fabricated MSC detector was higher than those of annealed MSCs reported in the literature, although the annealing step was not performed in this work. This means that surface and interfacial processes considerably affect the performance of radiation detectors, leaving room for further improvement of MSC properties by conducting additional annealing and/or interface passivation processes. More interestingly, both soft and hard X-rays were successfully detected at a zero-bias voltage. The continuous polarization induced by the internal electric field of MSCs promotes the movement of photocarriers to the opposite electrodes and their subsequent collection, leading to the generation of electrical signals. The direction-dependent photocurrent obtained in this work supports the above-mentioned carrier collection mechanism, which is also applicable to other perovskite single crystals with strong polarization-induced electric fields. Therefore, this work can serve as a guide for developing other self-powered perovskite high-energy X-ray detectors.


From the pre- to post-treatment period, the decline of hemoglobin level was 0.10 ± 0.89 g/dL, which was significantly less than that from baseline to pretreatment period . The change in hemoglobin level had a positive correlation with the change in HbA1c level , but did not correlate with the type of DPP-4 inhibitor or pretreatment eGFR. There was no significant change in peripheral blood white cell or platelet count during the same period. DPP-4 inhibitor ameliorates hemoglobin decline in DKD. The effect of DPP-4 inhibitor on hemoglobin is statistically significant but clinically modest, and did not correlate with the concomitant change in kidney function.Anemia typically develops early in the course of diabetic kidney disease (DKD). There are data to show that dipeptidyl-peptidase-4 (DPP-4) inhibitors affect hematopoietic growth factor activity and hemoglobin level. We retrospectively reviewed 443 DKD patients who were started on DDP-4 inhibitor therapy in 2019. Their hemoglobin level at baseline (6–12 months before treatment), pretreatment (0–6 months before treatment), and post-treatment periods (within 6 months after DPP-4 inhibitor), concomitant estimated glomerular filtration rate (eGFR), HbA1c, peripheral blood white cell and platelet counts were reviewed. The severity of kidney failure was classified according to the Kidney Disease: Improving Global Outcomes stages. The hemoglobin level had a small but significant decline from 11.98 ± 2.07 to 11.87 ± 2.12 g/dL from pretreatment to post-treatment period (paired Student  Approximately 30% to 40% of patients with type 1 diabetes and 20% of patients with type 2 diabetes develop DKD.,3 In the past 2 decades, DKD has become the most common cause of end-stage renal disease around the world.,5Diabetic kidney diseases (DKD) is one of the most serious complications of diabetes.,7 it is generally more severe and occurs at an earlier stage of renal failure in DKD. Anemia is an independent contributor to the pathogenesis and progression of other diabetes-related complications, especially left ventricular hypertrophy. In diabetic patients, correction of anemia improves the quality of life and might delay the progression of other diabetic complications.Although anemia is a common complication of chronic kidney disease (CKD) irrespective of the underlying cause, DPP-4 inhibitors are orally bioavailable compounds that prevent the cleavage of glucagon-like peptide-1, which is an incretin hormone with potent glucose-dependent insulinotropic actions, trophic effects on the pancreatic β-cells, and inhibitory effects on gastrointestinal secretion and motility, with the end result of lowering plasma glucose level.,12 In essence, DPP-4 inhibitors indirectly stimulate glucose- dependent insulin secretion and suppress glucagon secretion from pancreatic α-cells by increasing endogenous glucagon-like peptide-1 levels.In the past 2 decades, dipeptidylpeptidase-4 (DPP-4) inhibitors are increasingly used for the treatment of diabetes. DPP-4 cleaves a wide variety of substrates, including the chemokine stromal cell-derived factor-1 and, more importantly, the N-terminal of erythropoietin. A previous study showed that hematopoiesis after radiation or chemotherapy was enhanced in DPP-4 knock-out mice or mice receiving an orally active DPP-4 inhibitor. However, to the best of our knowledge, there is no human study on the relation between DPP-4 inhibitor therapy and anemia in DKD patients. We hypothesize that DPP-4 inhibitor therapy prevents the decline in hemoglobin level in DKD patients. In the present study, we examined the change in hemoglobin level in a large cohort of DKD patients who were started on DPP-4 inhibitor treatment.More recently, the effect of DPP-4 on the hematopoietic system is increasingly recognized. DPP-4, also known as CD26, is a peptidase expressed on the cell surface of most hematopoietic cells. and the severity of CKD was classified according to the Kidney Disease: Improving Global Outcomes stages. We also retrieved the baseline clinical and biochemical data of the patients from their electronic patient record.The study was approved by the Clinical Research Ethical Committee of the Chinese University of Hong Kong . All study procedures were in compliance with the Declaration of Helsinki. We retrospectively reviewed all DKD patients who were started on DPP-4 inhibitor in an university teaching hospital from January 1, 2019 to December 31, 2019. All patients were treated by their in-charge physician and the management was not affected by the study. DKD was defined as diabetic patients with urine albumin excretion above 30 mg:g-Cr or urine protein excretion above 0.5 g:g-Cr. Patients who had blood transfusion, recombinant human erythropoietin, iron deficiency, active malignancy, liver cirrhosis, and those receiving sodium-glucose cotransporter-2 (SGLT2) inhibitors or thiazolidinedione therapy during that period were excluded. In addition to the baseline demographic data and the details of DPP-4 inhibitor treatment, we retrieved their complete blood count, serum creatinine, and HbA1c levels from the Hong Kong Hospital Authority Clinical Data Analysis and Reporting System, from 12 months before the initiation of DPP-4 inhibitor treatment to 6 months after the treatment. Most patients had blood test every 2 to 3 months, but the frequency depended on the clinical need. The estimated glomerular filtration rate (eGFR) was calculated by the CKD-EPI equation,http://links.lww.com/MD/J405). As a self-control group, we defined the baseline period as between 6 and 12 months before the DPP-4 inhibitor was started .The primary outcome was the change in average hemoglobin level from the pretreatment to post-treatment period. The pretreatment period was defined as within 6 months before DPP-4 inhibitor was started, and post-treatment periods as the first 6 months after DPP-4 inhibitor was started . The sample size of this study was not calculated but we reviewed all eligible patients in our electronic clinical record database in order to ensure unbiased case selection. Data were expressed as means ± SD. Normality of data was checked by the Shapiro–Wilk Test. Data were compared by paired and un-paired Student http://links.lww.com/MD/J406. The baseline clinical and demographic characteristics for patients with complete hemoglobin profile were compared to that of the entire cohort in Table We reviewed 4133 patients who were started on DDP-4 inhibitor treatment; 443 (10.7%) had complete data on hemoglobin level before and after DPP-4 inhibitor treatment for analysis. The patient flow and reasons of exclusion are summarized in Supplementary Figure 2, For the 443 patients who had complete hemoglobin profile, there were 216 (48.7%) men, and the mean age was 67.8 ± 14.1 years. Among the 443 patients, 52.4% were treated with vildagliptin, 29.3% with alogliptin, 15.3% with sitagliptin, and 3.0% with linagliptin. Baseline clinical and demographic characteristics of the patients are summarized in Table t test, P < .0001). The decline of hemoglobin level in this period was 0.10 ± 0.89 g/dL; with 161 patients (37.2%) had hemoglobin decline ≥ 0.5 g/dL, and 92 patients (21.2%) had a decline ≥ 1.0 g/dL. The distribution histogram of the change in hemoglobin level is shown in Figure There was a small but significant decline in hemoglobin level from the pretreatment 11.98 ± 2.07 g/dL to post-treatment period 11.87 ± 2.12 g/dL . The hemoglobin level decreased by 0.24 ± 0.90 g/dL from baseline to pretreatment period, which was significantly more than that from pretreatment to post-treatment period . The change in hemoglobin level was not affected by the type of DPP-4 inhibitor (details not shown). We further performed subgroup analysis on the change of hemoglobin level according to the patients’ CKD stage, albuminuria stage, and the use of diuretic therapy, as summarized in Table Before the initiation of DPP-4 inhibitor therapy, the average hemoglobin level in the baseline period was 12.22 ± 2.01 g/dL, which showed a significant decline to the pretreatment period (paired Student P = .168). The pretreatment eGFR had a substantial correlation with the pretreatment hemoglobin level , but did not with the change in eGFR after DDP-4 inhibitor treatment .The eGFR did not change significantly from pretreatment to post-treatment period . The change in eGFR from pretreatment to post-treatment period was significantly better than that from the baseline to pretreatment period . The eGFR at the baseline period correlated with the hemoglobin level at the same time , but the change in eGFR from the baseline to pretreatment period did not correlate with the concomitant change in hemoglobin level . In this study population, there was no significant seasonal effect on the eGFR, hemoglobin level, or their changes in 6 months after DPP-4 inhibitor therapy . The use of concomitant medications  was not associated with the change in hemoglobin level.Before the initiation of DPP-4 inhibitor therapy, the average eGFR in the baseline period was 60.7 ± 36.2 mL/min/1.73mP < .0001). The change in HbA1c level from pre- to post-treatment period had a modest correlation with the change in hemoglobin level . There was no relation between the use of sulfonylurea, metformin, or insulin with the change in hemoglobin level. The relation between change in hemoglobin level and clinical parameters are further explored by multiple linear regression and summarized in Table The HbA1c level decreased significantly from pretreatment to post-treatment period . From the subgroup analysis, we found that the effect of DPP-4 inhibitor on hemoglobin is particularly prominent in patients with moderate to severe CKD or heavy albuminuria. More importantly, we observed a modest but significant positive correlation between the change in HbA1c and hemoglobin levels, indicating that the hematopoietic effect of DPP-4 inhibitor therapy is independent of the improvement in glycemic control. Similarly, the change in hemoglobin level did not correlate with the change in eGFR, suggesting that the hematopoietic effect of DPP-4 inhibitor therapy was not an indirect result of any effect on kidney function.Anemia is a common complication of CKD, and it is particularly common and severe in DKD as compared to non-diabetic CKD. DPP-4 gene knockout or DPP-4 inhibition improves the activity of these colony-stimulating factors in vitro and in vivo. As compared to the full-length GM-CSF, the DPP-4-truncated GM-CSF has reduced activity due to reduced receptor-binding affinity, ability of inducing GM-CSF receptor oligomerization and its downstream signaling capacity. In the present, we found that DPP-4 inhibitor had no appreciable effect on peripheral white cell or platelet count, suggesting that the effect in human is more prominent on erythropoietin than other colony-stimulating factors. This notion needs to be tested in further studies.The physiological mechanism of our observation is not entirely clear, but it is consistent with the findings of basic science studies that demonstrated a link between DPP-4 and hematopoiesis. It is well established that DPP-4 cleaves the N-terminals of granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3, and erythropoietin, and decreases their activity. and may affect different inhibitions to many enzymes that may affect hemoglobin levels. However, our results showed that the change in hemoglobin level was not affected by the type of DPP-4 inhibitor. A previous clinical trial demonstrated that patients treated with saxagliptin have a unexpected higher incidence of hospitalization for heart failure, this increased risk of heart failure hospitalization was not associated with an increased risk of cardiovascular death or all-cause mortality, the potential explanation is associate with hemodilution. On the other hand, a recent meta-analysis showed that treatment with DPP-4 inhibitors did not significantly increase cardiovascular outcomes in these patients with type 2 diabetes.DPP-4 inhibitors have quite heterogeneous chemical structures, and suggests a new pathway that may be pursued for the treatment of renal anemia. More recently, it is also reported that sodium-glucose transport protein 2 (SGLT2) inhibitors interacts with hypoxia-inducible factors and may promote erythrocytosis. Further studies would also be needed to delineate any additive or synergistic erythropoietic effects between DPP-4 inhibitor and SGLT2 inhibitor, both of which are increasingly used for the treatment of diabetes.It is important to note that our study hypothesis was that DPP-4 inhibitor prevents the decline in hemoglobin level in DKD patients. Although hemoglobin level decreased by only 0.1 g/dL within 6 months following DPP-4 inhibitor treatment, the rate of hemoglobin decline in the same group of patients was 0.24 g/dL during the 6 months period before DPP-4 inhibitor therapy was started, indicating that the rate of hemoglobin decline was reduced by nearly 60%. Since the change in hemoglobin level after DPP-4 inhibitor was compared to the change in same group of patients before DPP-4 inhibitor as historical control, the effect of DPP-4 inhibitor appears to be genuine and other patient related factors  seem unlikely. Nonetheless, we would emphasize although the effect of DPP-4 inhibitor on hemoglobin level is statistically significant, the actual effect is small, and the clinical significance is unknown. The effect of DPP-4 inhibitor on hemoglobin appeared to be particularly marked in CKD stage 3b and 5, but not stage 4, of which the reason is not entirely clear, and further study is deserved. Nonetheless, our study was a proof-of-the-concept and our result confirms an effect predicted by previous laboratory studies,,26 Since eGFR had a modest seasonal change in healthy subjects, the observational period should ideally be 12 months, but an extended observational period carries a risk of concurrent problems that may confound the hemoglobin and eGFR levels. Post hoc analysis of our study population also did not show any difference in kidney function, hemoglobin, or their changes following DPP-4 inhibitor between the rainy season (from April to September in Hong Kong) and the dry one , and this group of patients had better glycemic control and worse kidney function than those with incomplete data .The results of this paper was presented as poster in the World Congress of Nephrology, February 2022 (POS 356) and published as an abstract (Zeng LF, Chan GCK, Ng JCK, Szeto CC. DPP-4 inhibitor reduces the worsening of anemia in diabetic kidney disease. Kidney International Reports 2022; 7, S160-162; link: Conceptualization: Lingfeng Zeng, Cheuk Chun Szeto.Data curation: Gordon C.K. Chan, Jack K.C. Ng, Winston W.S. Fung.Formal analysis: Lingfeng Zeng, Jack K.C. Ng, Cheuk Chun Szeto.Funding acquisition: Kai-Ming Chow.Investigation: Lingfeng Zeng, Gordon C.K. Chan, Winston WS Fung.Methodology: Lingfeng Zeng, Gordon C.K Chan, Jack K.C. Ng, Winston W.S. Fung.Project administration: Jack K.C. Ng, Kai-Ming Chow.Supervision: Kai-Ming Chow, Cheuk Chun Szeto.Writing – original draft: Lingfeng Zeng.Writing – review & editing: Cheuk Chun Szeto.


A widespread outbreak of epidemics like Covid-19 is a lethal threat to physical and mental health. Recent studies reported a higher prevalence of mental problems in younger individuals, contrary to the general assumption expected in older people. Therefore, it is necessary to compare anxiety, stress, depression and PTSD (post-traumatic stress disorder) symptoms in different age groups during the Covid-19 crisis.A cross-sectional online survey was performed (from Dec. 2020 to Feb. 2021) on three age groups of elderly, middle-aged and young people. Data were collected by DASS-21  and IES-R  and analyzed using ANOVA, χ2 test and logistic regression analysis.P = 0.041), while the risk of depression, anxiety and stress did not differ significantly among the three age groups. Female gender, occupation, lower economic status, solitary life, and chronic disease were risk factors for psychological symptoms during the Covid-19 pandemic.Overall, 601 participants completed the questionnaires, including 23.3% of the elderly (≥ 60 years), 29.5% of the young (18–29 years) and 47.3% of the middle-aged (30–59 years) with 71.4% of women. The logistic regression analysis revealed that the risk of PTSD in young people was higher than in the elderly (β = 2.242, CI: 1.03–4.87, Findings on the higher odds ratio of PTSD symptoms in younger individuals have interestingly potential implications to meet the needs of mental health services during Covid-19.The online version contains supplementary material available at 10.1186/s12888-023-04677-0. The widespread occurrence of pandemics, such as the Covid-19, is closely related to the symptoms of mental health disorders and psychiatric diseases, regardless of infection . The detThe impact of the pandemic on mental health, including high rates of anxiety, depression, and post-traumatic stress disorder (PTSD) in the general population, has been reported in several countries across the Americas, Asia, the Middle East, and Europe , with fen < 400) have also demonstrated worsening psychological symptoms in groups of young people in the USA, Italy, India, Switzerland, and China [Contraction with Covid-19 and the mortality associated with it occur more in people of higher ages , but recnd China . One stund China . Howevernd China  and psycnd China  in the eThe health of the elderly is emphasized during the Covid-19 outbreak because they have a higher prevalence of pre-existing mental disorders and comorbidities, as well as the longest period of social isolation, which develops or worsens mental disorders. In addition, the Covid-19 trauma causes detestation and bias towards the patients or certain groups such as healthcare workers and the elderly . RecentlVarious factors are associated with the emergence of psychiatric symptoms in the Covid-19 crisis such as demographic factors, economic challenges, contact with social media, coping styles, quality of life, social support, psychological resilience, history of chronic diseases, and medical/psychiatric diseases, and government support policies –20.Trying to maintain mental health during the covid-19 is as important as trying to prevent and treat it in all age groups considering the significant effects of the Covid-19 on the mental health of younger people in a meta-analysis . TherefoThis cross-sectional study was conducted to assess the mental health and the impact of Covid-19 on the elderly compared to other age groups in Iran. Since the pandemic in Iran started on 19 February 2020, following its worldwide spread, the present study was conducted from December 2020 to February 2021 to investigate PTSD symptoms (after the first and second waves of 2020).The statistical population consisted of the elderly, middle-aged, and young individuals with eligibility for the study. According to the age guide of the Ministry of Health of Iran (integrated care plan), the age groups were as follows: young age group (18–29 years), middle-aged group (30–59) years and old age (60 and above). The inclusion criteria were people 18 years old and above with Iranian nationality and agreeing to participate in the study. The participants with an adverse condition in the previous three months were excluded from the study.The sample size was estimated based on Green's law . AccordiData collection tools included demographic characteristics questionnaire , Impact of Event Scale-Revised (IES-R) and Depression, Anxiety and Stress Scale (DASS).https://Survey.Porsline.Ir/S/G5rrHca/). The survey started with the statement: "Participation in the study is completely voluntary and that the information you would share with the researchers would be strictly confidential." In this way, only those who were willing to participate in the research entered the questionnaire completion stage. After confirming the understanding of this issue with the participants, the average completion of the questionnaires lasted 5 min.Taking into account social distance, the survey was conducted online in all provinces of the country. The questionnaires were designed on Porsline and shared on social media such as Telegram, WhatsApp, LinkedIn, and Facebook. We also distributed the questionnaires on social media channels in all provinces and cities to increase the level of responsiveness. Eligible people completed the questionnaire by clicking on the link , and good internal consistency with Cronbach α between 0.67–0.87. The Cronbach α coefficients for the IES-R subscales were from 0.84 to 0.93 (22).The IES-R was designed to parallel the DSM-IV criteria for PTSD symptoms. The scale has 22 items and consists of three subscales comprising intrusion, avoidance, and hyperarousal. The response range is from 0 (no symptoms) to 4 (extremely high level of symptoms) on a Likert scale. The IES-R yields a total score (0 to 88) and subscale scores can also be calculated. A score ≥ 33 was considered the cut-off point on the IES-R to qualify as an indicator of PTSD symptoms in an adult or senior population [The Depression, Anxiety and Stress Scale -21 Items (DASS-21) is a set of three self-report scales designed to measure the emotional states of depression, anxiety and stress over the past week. Each of the three DASS-21 scales contains seven items. Its response range is from 0 (never) to 3 (forever) on a Likert scale. Before interpreting the scores, the summed numbers in each subscale need to be multiplied by 2 . DASS intensity is rated from normal to very severe in five categories. DASS scores of ≥ 28 for depression, ≥ 20 for anxiety, and ≥ 34 for stress are considered very severe. The Persian version of the questionnaire has a reasonable degree of internal consistency, convergent and concurrent validities with Cronbach α of 0.94. Test–retest reliability for depression, stress, and anxiety scales were 0.77, 0.85, and 0.89, respectively .P < 0.05 was statistically significant.Once data were collected, all questionnaires were then entered into a customized Excel-based system. All data were subsequently imported into and analyzed via SPSS v. 22.0 . The assumption of normality of the data has been met , anxiety (p = 0.001), stress (p = 0.029) and hyperarousal subscale of PTSD (p = 0.035). Pairwise AVOVA revealed that young people had higher mean scores of depression than the middle-aged group. Also, elderly people had a higher mean score of anxiety, stress, and hyperarousal compared with the middle-aged group. There was no difference between young and elderly people regarding the mean scores of depression, stress, anxiety, and PTSD symptoms  than women. The results showed that the risk of PTSD in young people was higher than in the elderly . The non-healthcare workers had a higher risk of PTSD  than the healthcare workers. The risk of PTSD was higher in people who did not have enough family income  or had nearly enough family income  compared to those who had enough family income. Furthermore, the risk of PTSD was higher in people with underlying disease compared to healthy people . The people who lived with their family (spouse/children) had a lower risk of PTSD  than those who lived alone.The logistic regression analysis revealed that men had a lower risk of PTSD symptoms . In addition, non-healthcare workers had a higher risk of anxiety than healthcare workers , and the risk of stress in housewives  and employees  compared to health care workers.There was no significant difference in the risk of depression, anxiety and stress among the age groups. Logistic regression analysis showed that the risk of depression was higher in housewives than in healthcare workers  or had nearly enough family income  compared to those with enough family income.The risk of depression, anxiety and stress was higher in people who did not have enough family income . Also, the people living with a spouse/family had a lower risk of stress  than those who lived alone , depression (61% with cut-off DASS > 28), anxiety (62% with cut-off DASS > 20), and stress (62% with cut off DASS > 34) in three age groups of the study. In a similar cross-sectional study, in an Australian population of 4126 individuals with a range of 16–82 years, they were assessed in terms of potential psychological distress during the Covid-19 pandemic via DASS-21 and IES-R. The prevalence of moderate-to-severe PTSD symptoms was 43.3%. Also, the rate of moderate-to-severe symptoms in the population was 26.5% for depression, 20.3% for anxiety, and 21.2% for stress . The stuOur results revealed that the risk of depression, anxiety and stress did not differ among the elderly, middle-aged, and young groups. However, young people were at more risk of PTSD than the elderly. In line with our results, Traunmüller et al. reported that age was not an important factor in determining high PTSD symptoms during the Covid-19 pandemic . A studyContrary to our hypothesis, elderly people were not at higher risk of psychological symptoms like anxiety, depression, stress, and PTSD symptoms than young people during the pandemic. To explain the finding, the following hypotheses are presented. First, older people have greater resilience to the mental health effects of a crisis . Second,Of all of the demographic variables that were investigated to be the risk factors for depression , we found that women were at more risk for PTSD than men during the Covid-19 pandemic. Non-healthcare workers were also at higher risk of PTSD symptoms, anxiety and stress than healthcare workers. Similarly, depression and stress risks were higher in homemaker than in healthcare workers. The underlying diseases were a risk factor for PTSD, anxiety and stress. Individuals with low-economic status were at higher risk of PTSD, depression, anxiety and stress than higher-economic-status individuals. Finally, people who were living with their spouse/children had a lower risk of stress and PTSD than those living alone.In line with our results, some studies recognized that the female gender is a risk factor for PTSD symptoms, as well as anxiety, depression and stress , 25. PreThe results of the present study showed that there were fewer mental problems during the Covid-19 crisis in healthcare workers than in non-healthcare workers and homemakers. Most studies reported high levels of mental health problems in healthcare workers during Covid-19 –29. HoweIn line with previous research, our findings confirmed that chronic diseases aggravated the psychological consequences of Covid-19 . A studyNagasu et al. (2021) reported that people with low income perceived more psychological distress than other groups . AnotherThe findings of the present study indicated that people who were living with their spouse/family had a lower risk of stress and PTSD than those living alone. Ozbay et al. believed that social support is necessary for maintaining resilience, and psychological and physical health . It seemOur results highlighted an understanding of the impact of the Covid-19 pandemic on psychological distress among three population ages. The findings may be helpful to mental health professionals to recognize persons who are at a higher risk of developing psychological symptoms and those most in need of interventions during the initial stages of a social crisis. These results may help with the implementation of specific guidelines and protocols to hinder the developing symptoms of depression, anxiety, and PTSD in adults, middle-aged, and elderly populations during a social crisis.There were some limitations in the present study. Firstly, the method of data collection was an online survey. Thus, the sampling bias might have threatened the results. Secondly, we used self-report scales to assess PTSD symptoms, depression, anxiety, and stress. Further research is suggested to assess psychological disorders with a highly-reliable diagnosis such as clinical intervention. As the elderly participants are not active users of cyberspace, might be technophobic, or could not have internet access, they were not presented in this study. Thirdly, the participants in the online survey might have had different psychological situations during the first and second waves and the period between them. Fourthly, there was a lack of measurement invariance in the Persian versions of the instruments. Therefore, the generalization of the study results to every adult in Iran (people aged 18 and above) should be carried out with caution. Among the research strengths, we can mention population-based sampling, the comparison of three age groups, and accurate data analysis.During the Covid-19 pandemic, elderly people are not at higher risk for depression, anxiety, stress, and PTSD symptoms than the young or middle-aged group. Instead, young people were at more risk of psychological symptoms like PTSD than the elderly population. Female gender, non-healthcare workers, chronic diseases, lower economic status, and living alone are risk factors for psychological symptoms during the pandemic. These findings help identification of the populations at risk of mental health problems during Covid-19 and the implementation of national mental health intervention policies in other countries and regions.Additional file 1: Fig. 1A. Normal Q-Q Plot of Depression. Fig. 1B. Normal Q-Q Plot of Depression. Fig. 1C. Normal Q-Q Plot of Depression. Fig. 2A. Normal Q-Q Plot of Anxiety. Fig. 2B. Normal Q-Q Plot of Anxiety. Fig. 2C. Normal Q-Q Plot of Anxiety. Fig. 3A. Normal Q-Q Plot of Stress. Fig. 3B. Normal Q-Q Plot of Stress. Fig. 3C. Normal Q-Q Plot of Stress. Fig.4A. Normal Q-Q Plot ofPTSD total symptoms score. Fig.4B. Normal Q-Q Plot ofPTSD total symptoms score. Fig.4C. Normal Q-Q Plot ofPTSD total symptoms score. Fig.5A. Normal Q-Q Plot ofAvoidance. Fig.5B. Normal Q-Q Plot of Avoidance. Fig.5C. Normal Q-Q Plot of Avoidance. Fig.6A. Normal Q-Q Plot of Intrusion. Fig.6B. Normal Q-Q Plot of Intrusion. Fig.6C. Normal Q-Q Plot of Intrusion. Fig.7A. Normal Q-Q Plot of Hyperarousal. Fig.7B. Normal Q-Q Plot of Hyperarousal. Fig.7C. Normal Q-Q Plot of Hyperarousal.